On Mon, Jun 17, 2019 at 03:14:29PM +1200, Kai Huang wrote: > On Fri, 2019-06-14 at 13:56 +0200, Peter Zijlstra wrote: > > On Wed, May 08, 2019 at 05:44:09PM +0300, Kirill A. Shutemov wrote: > > > From: Kai Huang <kai.huang@xxxxxxxxxxxxxxx> > > > > > > KVM needs those variables to get/set memory encryption mask. > > > > > > Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx> > > > Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > > > --- > > > arch/x86/mm/mktme.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c > > > index df70651816a1..12f4266cf7ea 100644 > > > --- a/arch/x86/mm/mktme.c > > > +++ b/arch/x86/mm/mktme.c > > > @@ -7,13 +7,16 @@ > > > > > > /* Mask to extract KeyID from physical address. */ > > > phys_addr_t mktme_keyid_mask; > > > +EXPORT_SYMBOL_GPL(mktme_keyid_mask); > > > /* > > > * Number of KeyIDs available for MKTME. > > > * Excludes KeyID-0 which used by TME. MKTME KeyIDs start from 1. > > > */ > > > int mktme_nr_keyids; > > > +EXPORT_SYMBOL_GPL(mktme_nr_keyids); > > > /* Shift of KeyID within physical address. */ > > > int mktme_keyid_shift; > > > +EXPORT_SYMBOL_GPL(mktme_keyid_shift); > > > > > > DEFINE_STATIC_KEY_FALSE(mktme_enabled_key); > > > EXPORT_SYMBOL_GPL(mktme_enabled_key); > > > > NAK, don't export variables. Who owns the values, who enforces this? > > > > Both KVM and IOMMU driver need page_keyid() and mktme_keyid_shift to set page's keyID to the right > place in the PTE (of KVM EPT and VT-d DMA page table). > > MKTME key type code need to know mktme_nr_keyids in order to alloc/free keyID. > > Maybe better to introduce functions instead of exposing variables directly? > > Or instead of introducing page_keyid(), we use page_encrypt_mask(), which essentially holds > "page_keyid() << mktme_keyid_shift"? Yes, that's much better, because that strictly limits the access to R/O.
